CN104201982B - Photovoltaic system and its control method - Google Patents

Photovoltaic system and its control method Download PDF

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Publication number
CN104201982B
CN104201982B CN201410508157.5A CN201410508157A CN104201982B CN 104201982 B CN104201982 B CN 104201982B CN 201410508157 A CN201410508157 A CN 201410508157A CN 104201982 B CN104201982 B CN 104201982B
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China
Prior art keywords
control
inverter
photovoltaic
load
power
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CN201410508157.5A
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CN104201982A (en
Inventor
倪华
俞雁飞
代尚方
杨宗军
赵为
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Sungrow Power Supply Co Ltd
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Sungrow Power Supply Co Ltd
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Priority to CN201410508157.5A priority Critical patent/CN104201982B/en
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    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02MAPPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44Conversion of dc power input into ac power output without possibility of reversal by static converters
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02JCIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/381Dispersed generators
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02JCIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/381Dispersed generators
    • H02J3/382Dispersed generators the generators exploiting renewable energy
    • H02J3/383Solar energy, e.g. photovoltaic energy
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02JCIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2300/00Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20The dispersed energy generation being of renewable origin
    • H02J2300/22The renewable source being solar energy
    • H02J2300/24The renewable source being solar energy of photovoltaic origin
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00Energy generation through renewable energy sources
    • Y02E10/50Photovoltaic [PV] energy
    • Y02E10/56Power conversion systems, e.g. maximum power point trackers

Abstract

The invention discloses photovoltaic system and its control method, photovoltaic system includes photovoltaic output device, inverter, exchange interface arrangement, control device and AC load, the feeder ear of AC load is connected with the exchange outlet side of inverter, the control end of AC load is connected with control device, the control method is applied to control device, including:Control exchange interface arrangement keeps the off-state between inverter and power network;Start inverter, AC load is started afterwards;In the case of it is determined that photovoltaic system meets grid-connected conditions, control exchange interface arrangement connection inverter and power network.Photovoltaic system disclosed by the invention and its control method, the number of times that hiccup phenomenon occurs can just be reduced without additional configuration DC load, the cost and volume of photovoltaic system will not be increased, in addition, before inverter is grid-connected, AC load can make full use of the electric energy that photovoltaic output device is produced, it is to avoid from power network power taking.

Description

Photovoltaic system and its control method
Technical field
The invention belongs to technical field of photovoltaic power generation, more particularly to photovoltaic system and its control method.
Background technology
Photovoltaic DC-to-AC converter is used for photovoltaic output device (such as photovoltaic cell, or the photovoltaic group string being made up of photovoltaic cell Or photovoltaic array) direct current energy that sends is converted to AC energy.According to the output characteristics of known photovoltaic cell, photovoltaic cell At insufficient light (such as morning, dusk, or cloudy day), its output load capacity is weak, power swing is larger.In such case Under, although the open-circuit voltage of photovoltaic output device reaches the startup voltage of connected photovoltaic DC-to-AC converter, but once photovoltaic Grid-connected inverters run, and the output-power fluctuation of photovoltaic output device and the load effect of photovoltaic DC-to-AC converter can cause photovoltaic defeated Go out the output voltage step-down of device, when the output voltage of photovoltaic output device is unable to maintain that inverter continues to be incorporated into the power networks, will Photovoltaic DC-to-AC converter off-grid is caused to shut down, this start and stop phenomenon be commonly referred to as phenomenon of having the hiccups.Energy is carried in photovoltaic output device output band Power hiccup phenomenon can repeatedly occur when weaker, the mechanical life of grid-connected switch (such as relay, A.C. contactor) is quickly consumed, So as to the service life for causing photovoltaic system shortens, and the reliability of photovoltaic system is caused to reduce.
At present, in order to reduce the hiccup phenomenon of photovoltaic system, the technical scheme of use is:Increase in the DC side of photovoltaic system Plus can switching DC load (as shown in fig. 1), the output of photovoltaic output device electric energy is weaker or photovoltaic DC-to-AC converter at When off-grid state, DC load is put into, the electric energy exported by DC load consumption photovoltaic output device, to drag down photovoltaic output The output voltage of device, the voltage that is incorporated into the power networks for making it not reach photovoltaic DC-to-AC converter, prevents photovoltaic inverter grid-connected from running.Throwing After entering DC load, if the output voltage of photovoltaic output device remains able to reach the startup voltage of photovoltaic DC-to-AC converter, explanation The electric energy of photovoltaic output device output is more, enough runs photovoltaic inverter grid-connected, after photovoltaic inverter grid-connected operation again Disconnecting consumers device.
But, there is problems with existing technical scheme:Need the additional configuration DC load in photovoltaic system, increase The system cost of photovoltaic system, while DC load will take up room, increases the volume of photovoltaic system.
The content of the invention
In view of this, it is straight without configuration in addition it is an object of the invention to provide a kind of photovoltaic system and its control method Current load, it is possible to reduce the number of times that hiccup phenomenon occurs in photovoltaic system.
To achieve the above object, the present invention provides following technical scheme:
A kind of control method of photovoltaic system, the photovoltaic system includes photovoltaic output device, inverter, exchange interface Device, control device and AC load, the feeder ear of the AC load are connected with the exchange outlet side of the inverter, institute The control end for stating AC load is connected with the control device, and the control method is applied to the control device, including:
The control exchange interface arrangement keeps the off-state between the inverter and power network;
Start the inverter, the AC load is started afterwards;
In the case of it is determined that the photovoltaic system meets grid-connected conditions, control the exchange interface arrangement connection described inverse Become device and the power network, wherein the grid-connected conditions are used to determine whether the electric energy of the photovoltaic output device output can be tieed up Hold the inverter and the AC load stable operation.
Preferably, determine whether the photovoltaic system meets grid-connected conditions and include:
Judge the DC side input voltage of the inverter whether more than voltage threshold;
If, it is determined that the photovoltaic system meets grid-connected conditions;
Otherwise, whether time delay Preset Time, re-execute the DC side input voltage for judging the inverter more than electricity The step of pressure threshold value.
Preferably, determine whether the photovoltaic system meets grid-connected conditions and include:
Judge whether the inverter and the AC load remain on not power down in preset time period;
If, it is determined that the photovoltaic system meets grid-connected conditions;
Otherwise, time delay Preset Time, starts the inverter and the AC load, re-executes and judges the inversion The step of whether device and the AC load remain on not power down in preset time period.
Preferably, determine whether the photovoltaic system meets grid-connected conditions and include:
The DC side input voltage for controlling the inverter is a fixed value;
Judge the AC power output of the inverter whether more than power threshold;
If, it is determined that the photovoltaic system meets grid-connected conditions;
Otherwise, whether time delay Preset Time, re-execute the AC power output for judging the inverter more than work( The step of rate threshold value.
Preferably, determine whether the photovoltaic system meets grid-connected conditions and include:
It is a fixed value to control the inverter and the power and value of AC load consumption;
Judge whether the inverter is able to maintain that in the operation of current power point;
If, it is determined that the photovoltaic system meets grid-connected conditions;
Otherwise, time delay Preset Time, re-executes and judges whether the inverter is able to maintain that in current power point fortune Capable step.
Preferably, when the control device is powered by the DC side of the photovoltaic system, the inverter is being started After the AC load, the control method also includes:Limit the operation work(of the inverter and the AC load Rate, to prevent the control device power down.
Preferably, the AC load is connected by switch with the exchange outlet side of the inverter, the switch Control end is connected with the control device, control the exchange interface arrangement connect the inverter and the power network it Afterwards, the control method also includes:Switched off described in control.
Invention additionally discloses a kind of photovoltaic system, including photovoltaic output device, inverter, exchange interface arrangement, control Device and AC load, the feeder ear of the AC load are connected with the exchange outlet side of the inverter, and the exchange is negative The control end of load is connected with the control device;
The control device control exchange interface arrangement keeps the off-state between the inverter and power network, Start the inverter afterwards, start the AC load, in the case of it is determined that the photovoltaic system meets grid-connected conditions, The control exchange interface arrangement connects the inverter and the power network, wherein the grid-connected conditions are used to determine the light Whether the electric energy of volt output device output is able to maintain that the inverter and the AC load stable operation.
Preferably, the AC load is including any one or more in fan, heater and dehumidifier.
Preferably, the exchange interface arrangement includes grid-connected switch, the control end of the grid-connected switch and the control dress Put connection.
As can be seen here, beneficial effects of the present invention are:The control method of photovoltaic system disclosed by the invention, in inverter In the state of off-grid operation, the electric energy exported by the AC load consumption photovoltaic output device in photovoltaic system, in photovoltaic output Electric energy that device is produced is more when being able to maintain that inverter and AC load stable operation, then controls the grid-connected fortune of inverter OK, due to photovoltaic output device produce electric energy it is more, therefore control device can continuous service without occur off-grid shut down, Compared with prior art, the number of times that photovoltaic system occurs hiccup phenomenon can be just reduced without additional configuration DC load, will not Increase the cost and volume of photovoltaic system.In addition, before inverter is grid-connected, AC load can make full use of photovoltaic to export The electric energy that device is produced, it is to avoid from power network power taking.
Brief description of the drawings
In order to illustrate more clearly about the embodiment of the present invention or technical scheme of the prior art, below will be to embodiment or existing The accompanying drawing to be used needed for having technology description is briefly described, it should be apparent that, drawings in the following description are only this Inventive embodiment, for those of ordinary skill in the art, on the premise of not paying creative work, can also basis The accompanying drawing of offer obtains other accompanying drawings.
Fig. 1 is in the prior art in the structural representation of photovoltaic system configuring direct current load;
Fig. 2 is a kind of flow chart of control method of photovoltaic system disclosed by the invention;
Fig. 3 is the flow chart of another control method of photovoltaic system disclosed by the invention;
Fig. 4 is the flow chart of another control method of photovoltaic system disclosed by the invention;
Fig. 5 is the flow chart of another control method of photovoltaic system disclosed by the invention;
Fig. 6 is the flow chart of another control method of photovoltaic system disclosed by the invention;
Fig. 7 is the structural representation of photovoltaic system disclosed by the invention;
Fig. 8 is the part-structure schematic diagram of photovoltaic system disclosed by the invention.
Specific embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is carried out clear, complete Site preparation is described, it is clear that described embodiment is only a part of embodiment of the invention, rather than whole embodiments.It is based on Embodiment in the present invention, it is every other that those of ordinary skill in the art are obtained under the premise of creative work is not made Embodiment, belongs to the scope of protection of the invention.
The present invention discloses a kind of control method of photovoltaic system, compared with prior art, without the load of other configuring direct current, The number of times that hiccup phenomenon occurs in photovoltaic system can just be reduced.
The structure of the photovoltaic system in the present invention is as shown in fig. 7, comprises photovoltaic output device 100, inverter 200, friendship Stream interface device 300, control device 400 and AC load 500.Wherein, photovoltaic output device 100 is straight with inverter 200 Stream input side connection, the exchange outlet side of inverter 200 is connected by exchanging interface arrangement 300 with power network, AC load 500 Feeder ear be connected with the exchange outlet side of inverter 200, in addition, inverter 200, exchange interface arrangement 300 and hand over The control end of current load 500 is connected with control device 400 respectively.Photovoltaic output device 100 is used to convert the solar into electric energy, The direct current that photovoltaic output device 100 is exported is converted to alternating current by inverter 200, afterwards by exchanging interface arrangement 300 Transmit to power network, in addition, AC load 500 can be powered by inverter 200.Explanation is needed exist for, in order to ensure light The stable operation of volt system, will set the AC loads such as fan, dehumidifier, heater in photovoltaic system, in existing photovoltaic system In system, AC load is connected with power network, is powered by power network, and in the present invention by the feeder ear of AC load 500 with it is inverse Become the exchange outlet side connection of device 200.
Referring to Fig. 2, Fig. 2 is a kind of flow chart of control method of photovoltaic system disclosed by the invention.The control method should For the control device in photovoltaic system, including:
Step S21:Control exchange interface arrangement keeps the off-state between inverter and power network.
Photovoltaic system, in just start, is off-state between inverter and power network.Control device control exchange interface Device keeps the off-state between inverter and power network, that is, control inverter to be in off-grid state.
Step S22:Start inverter, AC load is started afterwards.
Control device is after control inverter is in off-grid state, then controls inverter to start, now, inversion dress Put and the direct current that photovoltaic output device is exported is converted into alternating current.Afterwards, control device control AC load starts, and exchange is negative Carry the alternating current of consumption inverter output.
Step S23:In the case of it is determined that photovoltaic system meets grid-connected conditions, control exchange interface arrangement connection inversion dress Put and power network.Wherein, the grid-connected conditions be used for determine photovoltaic output device output electric energy whether be able to maintain that inverter and AC load stable operation.
Control device judges whether photovoltaic system meets grid-connected conditions after inverter and AC load is started, if Meet grid-connected conditions, just control exchange interface arrangement connection inverter and power network, that is, control inverter enters grid-connected State.If being unsatisfactory for grid-connected conditions, can again judge whether photovoltaic system meets grid-connected bar after time delay Preset Time Part.
Explanation is needed exist for, when photovoltaic system meets grid-connected conditions, it may be determined that the output of photovoltaic output device Electric energy is able to maintain that the stable operation of inverter and AC load, that is to say, that the electric energy of photovoltaic output device output is more, Photovoltaic inverter grid-connected is run and is occurred without hiccup phenomenon enough, now control photovoltaic inverter grid-connected to run again.
The control method of photovoltaic system disclosed by the invention, in the state of the operation of inverter off-grid, by photovoltaic system In AC load consumption photovoltaic output device output electric energy, the electric energy that produces in photovoltaic output device is more be able to maintain that it is inverse When becoming device and AC load stable operation, then inverter is controlled to be incorporated into the power networks, due to the electric energy that photovoltaic output device is produced It is more, thus control device can continuous service without occur off-grid shut down, it is compared with prior art, straight without additional configuration Current load can just reduce the number of times that photovoltaic system occurs hiccup phenomenon, will not increase the cost and volume of photovoltaic system.In addition, Before inverter is grid-connected, AC load can make full use of the electric energy that photovoltaic output device is produced, it is to avoid from power network power taking.
In implementation, judge whether photovoltaic system meets grid-connected conditions, there are various different implementations.Carry out separately below Explanation.
Referring to Fig. 3, Fig. 3 is the flow chart of another control method of photovoltaic system disclosed by the invention.The control method The control device in photovoltaic system is applied to, including:
Step S31:Control exchange interface arrangement keeps the off-state between inverter and power network.
Step S32:Start inverter, AC load is started afterwards.
Step S33:Whether the DC side input voltage of inverter is judged more than voltage threshold, if so, then performing step S34, otherwise, performs step S35.
After control inverter and AC load operation, if the DC side input voltage of inverter is remained able to It is maintained at more than voltage threshold, the DC side input voltage of such as inverter can be maintained at more than line voltage peak value, It is assured that photovoltaic system meets grid-connected conditions.
Step S34:Determine that photovoltaic system meets grid-connected conditions, control exchange interface arrangement connection inverter and power network.
Step S35:Time delay Preset Time, re-executes step S33.
Control method shown in Fig. 3 of the present invention, after inverter and AC load is started, if inverter is straight Stream side input voltage is maintained to more than voltage threshold, shows that inverter power output disclosure satisfy that self-operating work( The requirement of consumption, it is grid-connected after can be to power network transmit power, without absorbed power, photovoltaic system meets grid-connected requirement, control Be not in hiccup phenomenon after inverter is incorporated into the power networks.
Referring to Fig. 4, Fig. 4 is the flow chart of another control method of photovoltaic system disclosed by the invention.The control method The control device in photovoltaic system is applied to, including:
Step S41:Control exchange interface arrangement keeps the off-state between inverter and power network.
Step S42:Start inverter, AC load is started afterwards.
Step S43:Judge whether inverter and AC load remain on not power down in preset time period, if so, Step S44 is then performed, otherwise, step S45 is performed.
After control inverter and AC load operation, if inverter and AC load can be in a period of times Inside remain on without power down, it is possible to determine that photovoltaic system meets grid-connected requirement.
Step S44:Determine that photovoltaic system meets grid-connected conditions, control exchange interface arrangement connection inverter and power network.
Step S45:Time delay Preset Time, starts inverter and AC load, re-executes step S43.
Control method shown in Fig. 4 of the present invention, after inverter and AC load is started, if inverter and friendship Current load can be remained on without power down in preset time period, show that inverter power output disclosure satisfy that self-operating The requirement of power consumption, it is grid-connected after can be to power network transmit power, without absorbed power, photovoltaic system meets grid-connected requirement, control Be not in hiccup phenomenon after inverter processed is incorporated into the power networks.
Referring to Fig. 5, Fig. 5 is the flow chart of another control method of photovoltaic system disclosed by the invention.The control method The control device in photovoltaic system is applied to, including:
Step S51:Control exchange interface arrangement keeps the off-state between inverter and power network.
Step S52:Start inverter, AC load is started afterwards.
Step S53:The DC side input voltage for controlling inverter is a fixed value.
Step S54:Whether the AC power output of inverter is judged more than power threshold, if so, then performing step S55, otherwise, performs step S56.
After control inverter and AC load operation, the DC side input voltage of inverter is controlled to be fixed for one Value, if the AC power output of inverter is more than power threshold, is greater than the grid-connected loss power of inverter itself, It is to ensure that inverter has power output after grid-connected, without from power network absorbed power, determining that photovoltaic system meets simultaneously Net is required.
Step S55:Determine that photovoltaic system meets grid-connected conditions, control exchange interface arrangement connection inverter and power network.
Step S56:Time delay Preset Time, re-executes step S53.
Control method shown in Fig. 5 of the present invention, after inverter and AC load is started, controls the straight of inverter Stream input voltage is a fixed value, if the AC power output of inverter is more than power threshold, shows that inverter is defeated Go out the requirement that power disclosure satisfy that self-operating power consumption, it is grid-connected after can be to power network transmit power, without absorbed power, photovoltaic System meets grid-connected requirement, is not in hiccup phenomenon after control inverter is incorporated into the power networks.
Referring to Fig. 6, Fig. 6 is the flow chart of another control method of photovoltaic system disclosed by the invention.The control method The control device in photovoltaic system is applied to, including:
Step S61:Control exchange interface arrangement keeps the off-state between inverter and power network.
Step S62:Start inverter, AC load is started afterwards.
Step S63:It is a fixed value to control inverter and the power and value of AC load consumption.
Step S64:Judge whether inverter is able to maintain that in the operation of current power point, if so, step S65 is then performed, Otherwise, step S66 is performed.
After control inverter and AC load operation, the power sum of control inverter and AC load consumption It is a fixed value, if inverter is able to maintain that in the operation of current power point, it becomes possible to ensure have after inverter is grid-connected Power output, without from power network absorbed power, determining that photovoltaic system meets grid-connected requirement.
Step S65:Determine that photovoltaic system meets grid-connected conditions, control exchange interface arrangement connection inverter and power network.
Step S66:Time delay Preset Time, re-executes step S63.
Control method shown in Fig. 6 of the present invention, after inverter and AC load is started, controls inverter and friendship The power sum of current load consumption is a fixed value, if inverter is able to maintain that in the operation of current power point, shows inversion Device power output disclosure satisfy that the requirement of self-operating power consumption, it is grid-connected after can be to power network transmit power, without absorbing work( Rate, photovoltaic system meets grid-connected requirement, is not in hiccup phenomenon after control inverter is incorporated into the power networks.
When the control device in photovoltaic system is when being powered by the DC side of photovoltaic system, in present invention control disclosed above In method processed, after inverter and AC load is started, also comprise the following steps:Limitation inverter and AC load Operation power, to prevent control device power down.When judged result is "No" for example in step S64, limitation inversion can be increased The step of operation power of device and AC load is less than set power, to prevent inverter power down.Perform step again afterwards Rapid S66.
In addition, when the AC load in photovoltaic system is connected by switch with the exchange outlet side of inverter, and open In the case that the control end of pass is connected with control device, in present invention control method disclosed above, in control exchange interface After connection inverter and power network, also comprise the following steps:Controlling switch disconnects.
Explanation is needed exist for, when the AC load of photovoltaic system includes multiple equipment, each equipment can be configured It is connected with the exchange outlet side of inverter by a switch respectively, in control exchange orifice inverter and power network Afterwards, partial switch can be disconnected according to the operation demand of system, that is to say, that part AC load in photovoltaic system with it is inverse The connection for becoming device is disconnected, and the electric energy that part AC load is still produced by photovoltaic output device is powered.For example:In photovoltaic , it is necessary to fan carries out auxiliary heat dissipation when system local environment temperature is higher, if the electric energy that photovoltaic output device is produced is more, that The electric energy of photovoltaic output device generation can be continued with for fan is powered.
Invention additionally discloses a kind of photovoltaic system, its structure is as shown in fig. 7, comprises photovoltaic output device 100, inverter 200th, exchange interface arrangement 300, control device 400 and AC load 500.
Wherein, photovoltaic output device 100 is connected with the direct current input side of inverter 200, and the exchange of inverter 200 is defeated Go out side and be connected with power network by exchanging interface arrangement 300, the feeder ear of AC load 500 exchanges output with inverter 200 Side connect, in addition, inverter 200, exchange interface arrangement 300 and AC load 500 control end respectively with control device 400 connections.Photovoltaic output device 100 is used to convert the solar into electric energy, and inverter 200 is defeated by photovoltaic output device 100 The direct current for going out is converted to alternating current, is transmitted to power network by exchanging interface arrangement 300 afterwards, in addition, AC load 500 can be with Powered by inverter 200.Explanation is needed exist for, in order to ensure the stable operation of photovoltaic system, to be set in photovoltaic system Put the AC loads such as fan, dehumidifier, heater, in existing photovoltaic system, AC load be connected with power network, by power network Power supply, and the feeder ear of AC load 500 is connected with the exchange outlet side of inverter 200 in the present invention.
It should be noted that AC load 500, is not limited solely to three of the above type AC load.
After photovoltaic system is started, the control exchange interface arrangement 300 of control device 400 keeps inverter 200 with electricity Off-state between net, starts inverter 200 afterwards, starts AC load 500, it is determined that photovoltaic system meets grid-connected bar In the case of part, control exchange interface arrangement 300 connection inverter 200 and power network, wherein grid-connected conditions are used to determine light Whether the electric energy of the volt output of output device 100 is able to maintain that inverter 200 and the stable operation of AC load 500.
Photovoltaic system disclosed by the invention, in the state of the operation of inverter off-grid, is born by the exchange in photovoltaic system The electric energy of consumption photovoltaic output device output is carried, the electric energy produced in photovoltaic output device is more to be able to maintain that inverter and friendship During current load stable operation, then inverter is controlled to be incorporated into the power networks, because the electric energy that photovoltaic output device is produced is more, therefore control Device processed can continuous service without occur off-grid shut down, compared with prior art, can without additional configuration DC load To reduce the number of times that photovoltaic system occurs hiccup phenomenon, the cost and volume of photovoltaic system will not be increased.In addition, in inverter Before grid-connected, AC load can make full use of the electric energy that photovoltaic output device is produced, it is to avoid from power network power taking.
In addition, in photovoltaic system disclosed by the invention, photovoltaic output device 100, inverter 200, exchange interface arrangement 300 and AC load 500 have various different structures.Illustrate separately below.
Photovoltaic output device 100 can be single photovoltaic module, multiple photovoltaic modulies, single photovoltaic group string, Duo Geguang Volt group string or photovoltaic array.
Inverter 200 includes DC/AC converters, and the direct current of input is converted to exchange electricity output by DC/AC converters. Preferably, inverter 200 can also include filter, such as AC reactor.
Exchange interface arrangement 300 includes grid-connected switch, and the control end of the grid-connected switch is connected with control device 400, is used for Inverter 200 and power network are connected under the control of control device 400, or disconnects the company between inverter 200 and power network Connect.Grid-connected switch can be AC relay or A.C. contactor.
Preferably, exchange interface arrangement 300 can also include AC filter installation, exchange protector, conflux One or more in power distribution equipment, Industrial Frequency Transformer.
Wherein, AC filter installation is used to improve AC wave shape quality or EMI environment, and AC filter installation can be used AC reactor, AC capacitor, differential mode inductance, common mode inductance, X electric capacity or Y capacitance.
Exchange protector is used to carry out equipment, personal safety and power network security protection, and exchange protector includes anti- Thunder device, surge protection device, exchange fuse and AC circuit breaker in one or more.
The power distribution equipment that confluxes is used to for multiple alternating current line of force inlet wires to conflux into less alternating current line of force outlet, can be with Connection disconnects alternating current line of force inlet wire and alternating current line of force outlet.
Industrial Frequency Transformer is used to realizing the electrical isolation of photovoltaic system and power network, and voltage class conversion.
AC load 500 is including any one or more in fan, heater and dehumidifier.
Preferably, DC interface device can be set between photovoltaic output device 100 and inverter 200.
DC interface device includes the termination that confluxes, and the termination that confluxes is used for many of photovoltaic output device 100 Individual DC power line inlet-wire parallel connection, pools less DC power line outlet, can also connect or disconnect direct current power Line inlet wire and DC power line outlet.
Preferably, DC converter, DC filtering device and direct current protection dress can also be set in DC interface device One or more in putting.
Wherein, DC converter includes isolated DC converting means or non-isolated DC converter, will be straight Stream electricity is converted to the direct current output with different qualities, the direct current of the voltage change for for example exporting photovoltaic output device 100 Be converted to the direct current of voltage stabilization.
DC filtering device is used to improve DC waveform quality or EMI (electromagnetic interference) environment, and DC filtering device can With using direct current reactor, direct current capacitors, differential mode inductance, common mode inductance, X electric capacity or Y capacitance.
Direct current protector is used to carry out equipment and personal safety security protection, and direct current protector is filled including lightning protection Put, surge protection device, GFDI (ground fault detection and switchgear), anti-reverse diode, DC fuse and direct current fuse One or more in device.
Referring to Fig. 8, Fig. 8 is the part-structure schematic diagram of photovoltaic system disclosed by the invention.Wherein, inverter 200 is wrapped Include DC/AC converters 201 and filter reactance 202.Exchange interface arrangement 300 include it is grid-connected switch 301, electromagnetic interface filter 302 and every From transformer 303.AC load 500 includes ac fan 501, heater 502 and dehumidifier 503.
It should be noted that AC load 500, is not limited solely to three of the above type AC load.
Finally, in addition it is also necessary to explanation, herein, such as first and second or the like relational terms be used merely to by One entity or operation make a distinction with another entity or operation, and not necessarily require or imply these entities or operation Between there is any this actual relation or order.And, term " including ", "comprising" or its any other variant meaning Covering including for nonexcludability, so that process, method, article or equipment including a series of key elements not only include that A little key elements, but also other key elements including being not expressly set out, or also include for this process, method, article or The intrinsic key element of equipment.In the absence of more restrictions, the key element limited by sentence "including a ...", does not arrange Except also there is other identical element in the process including the key element, method, article or equipment.
Each embodiment is described by the way of progressive in this specification, and what each embodiment was stressed is and other The difference of embodiment, between each embodiment identical similar portion mutually referring to.For device disclosed in embodiment For, because it is corresponded to the method disclosed in Example, so description is fairly simple, related part is said referring to method part It is bright.
The foregoing description of the disclosed embodiments, enables professional and technical personnel in the field to realize or uses the present invention. Various modifications to these embodiments will be apparent for those skilled in the art, as defined herein General Principle can be realized in other embodiments without departing from the spirit or scope of the present invention.Therefore, the present invention The embodiments shown herein is not intended to be limited to, and is to fit to and principles disclosed herein and features of novelty phase one The scope most wide for causing.

Claims (9)

1. a kind of control method of photovoltaic system, the photovoltaic system includes photovoltaic output device, inverter, exchange interface dress Put, control device and AC load, the AC load is for for ensureing the exchange that the photovoltaic system stable operation is configured Load, it is characterised in that the feeder ear of the AC load is connected with the exchange outlet side of the inverter, the exchange is negative The control end of load is connected with the control device, and the control method is applied to the control device, including:
The control exchange interface arrangement keeps the off-state between the inverter and power network;
Start the inverter, the AC load is started afterwards, the AC load includes fan, dehumidifier and heater In it is any one or more;
In the case of it is determined that the photovoltaic system meets grid-connected conditions, the exchange interface arrangement is controlled to connect the inversion dress Put with the power network, wherein the grid-connected conditions are used to determine whether the electric energy of photovoltaic output device output is able to maintain that institute State inverter and the AC load stable operation.
2. control method according to claim 1, it is characterised in that determine whether the photovoltaic system meets grid-connected conditions Including:
Judge the DC side input voltage of the inverter whether more than voltage threshold;
If, it is determined that the photovoltaic system meets grid-connected conditions;
Otherwise, whether time delay Preset Time, re-execute the DC side input voltage for judging the inverter more than voltage threshold The step of value.
3. control method according to claim 1, it is characterised in that determine whether the photovoltaic system meets grid-connected conditions Including:
Judge whether the inverter and the AC load remain on not power down in preset time period;
If, it is determined that the photovoltaic system meets grid-connected conditions;
Otherwise, time delay Preset Time, starts the inverter and the AC load, re-executes and judges the inverter The step of whether not power down being remained on the AC load in preset time period.
4. control method according to claim 1, it is characterised in that determine whether the photovoltaic system meets grid-connected conditions Including:
The DC side input voltage for controlling the inverter is a fixed value;
Judge the AC power output of the inverter whether more than power threshold;
If, it is determined that the photovoltaic system meets grid-connected conditions;
Otherwise, whether time delay Preset Time, re-execute the AC power output for judging the inverter more than power-threshold The step of value.
5. control method according to claim 1, it is characterised in that determine whether the photovoltaic system meets grid-connected conditions Including:
It is a fixed value to control the inverter and the power and value of AC load consumption;
Judge whether the inverter is able to maintain that in the operation of current power point;
If, it is determined that the photovoltaic system meets grid-connected conditions;
Otherwise, time delay Preset Time, re-executes and judges whether the inverter is able to maintain that in the operation of current power point Step.
6. control method according to any one of claim 1 to 5, it is characterised in that when the control device is by described When the DC side of photovoltaic system is powered, after the inverter and the AC load is started, the control method is also wrapped Include:
The operation power of the inverter and the AC load is limited, to prevent the control device power down.
7. control method according to any one of claim 1 to 5, it is characterised in that the AC load is by switch It is connected with the exchange outlet side of the inverter, the control end of the switch is connected with the control device, it is described in control Exchange interface arrangement is connected after the inverter and the power network, and the control method also includes:The control switch is disconnected Open.
8. a kind of photovoltaic system, including photovoltaic output device, inverter, exchange interface arrangement, control device and AC load, The AC load is for for ensureing the AC load that the photovoltaic system stable operation is configured, it is characterised in that
The feeder ear of the AC load is connected with the exchange outlet side of the inverter, the control end of the AC load with The control device connection, the AC load is including any one or more in fan, heater and dehumidifier;
The control device control exchange interface arrangement keeps the off-state between the inverter and power network, afterwards Start the inverter, start the AC load, in the case of it is determined that the photovoltaic system meets grid-connected conditions, control The exchange interface arrangement connects the inverter and the power network, wherein the grid-connected conditions are used to determine that the photovoltaic is defeated Whether the electric energy for going out device output is able to maintain that the inverter and the AC load stable operation.
9. photovoltaic system according to claim 8, it is characterised in that the exchange interface arrangement includes grid-connected switch, institute The control end for stating grid-connected switch is connected with the control device.
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